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iHasApp only uses public and documented methods, and as a result is App Store safe. To date, over one hundred apps have been submitted and approved with iHasApp integrated.
While iHasApp is able to detect the existence of many iOS apps, unfortunately not every app implements the protocol iHasApp uses for detection. It is not a perfect system, but currently the best option.
iHasApp uses two primary heuristics to determine which apps are installed on a device. The first is by checking the existence of certain URL schemes (the inter-app communication protocol on iOS). The second is by examining the active processes list for running apps.
App detections usually take less than one or two seconds from start to finish. Depending on the device model and network conditions, detections can take as little as 500ms or as long as five seconds.